BIOL398-04/S15:Jeffrey Crosson Week 2
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New Biological Terms
- Proline: a heterocyclic, nonpolar, ring-like amino acid that is present in all proteins studied to date
- Gram-negative: the group of bacteria, or a related one, that takes the color of the counterstain after gram staining
- Transferase: the suffix to the name of an enzyme indicating that it transfers a specific grouping between molecules
- Urea: final nitrogenous excretion product of many organisms, a molecules created from ammonia and carbon dioxide as a result of the urea cycle
- Acetaldehyde: oxidation product of ethanol, also called ethanal
- Dehydrogenase: anenzyme that oxidizes a substrate by transferring hydrogen to an acceptor, this is used in the cytochrome system in respiration to produce ATP
- Synthetase: catalyse synthesis of molecules, breaks down a nucleotide triphosphate.
- Permease: a membrane-bound protein in bacteria that transports specific substances in or out of the cell
- Oligonucleotide: linear sequence of up to 20 nucleotides joined by phosphodiester bonds
- Northern analysis: similar to the southern blot analysis, used mostly to separate and identify rNA fragments
Outline
- Main point
- Ammonia concentration, not flux, may determine amount of nitrogen metabolism
- Significance
- Cells may have a control system via ammonia for nitrogen metabolism
- Other experiments
- Shows that flux could have been main driving force over concentration, but due to poor setup
- General procedure
- Yeast grown with fixed glucose concentrations and varying ammonia concentrations from 29 - 61 mM
- Phenomena
- Metabolism is regulated by extracellualr and intracellular ammonia concentrations, alpha ketoglutarate, glutamine, or glutamate,
- Conclusion
- Ammonia concentration may determine nitrogen metabolism in Sacchoromyces cerevisiae cells if so, which identifies the existence of a nitrogen control system
Figure 1B
When input ammonia concentration is above 44 mM, the CO2 production and O2 consumption remained relatively constant. However, at 29 mM the CO2 production increased and O2 consumption decreased. These data indicate that, except at 29 mM ammonia in the feed, no significant changes in the carbon metabolism occurred when the ammonia concentration in the feed was increased and the culture was switched from ammonia limitation to ammonia excess.
